▎ 摘　　要

The unique combination of DNA bases is essential for storing genetic information. A reliable and accurate electrochemical sensor based on a gold/palladium-polypyrrole/graphene nanocomposite (Au/Pd-PPy/GR) has been prepared to individually and simultaneously detect guanine (G), adenine (A), thymine (T), and cytosine (C). The bimetallic nanomaterial (Au/Pd-PPy) is used to enhance the sensing performance of DNA bases, and the GR could further increase the electroactive area and amplify the electrochemical response. As expected, the electrochemical sensor shows excellent electrocatalytic activity with well-separated current responses at 0.704 V (G), 0.976 (A), 1.164 (T), and 1.348 V (C). The prepared sensor exhibits the linear range of 1-350 mu M for G, 5-300 mu M for A, 20-900 mu M for T, and 10-700 mu M for C. The developed device is also demonstrated as an excellently sensitive and highly selective sensor to identify the four bases in calf thymus DNA, which provides the application of electrochemical sensors in bioscience.